The european U20 championships overall wont be as strong as the U23 championships, but i think that in some disciplines the level might be better than at the U23 championships. In mens pole vault it might take 5.70 m to medal and in womens heptathlon it will probably take 6100 points to medal. In addition to that i clearly prefer Grosseto compared to Bydgoszcz, we can see the first international competitions of some future stars (Tortu, Ingebrigtsen, Duplantis, Raffin, Ruckstuhl) and the results will be pretty unpredictable, considering the age of those athletes. Sadly Tortu will only compete in one event, but there are other athletes who could win multiple individual golds (Sclabas in womens 1500/3000 m, Ingebrigtsen in mens 1500/5000/3000 m SC, Ruckstuhl in womens heptathlon/javelin throw). I think Switzerland might even win the medal table ...
Italy looks also strong, they should win at least 3 gold medals, Finland also seems to have some nice talents, as well as Slovenia and the Czech Republic.
About the U23 championships:
I think only the following talents might medal at world championships in the future:
Klosterhalfen, Can, Visser, the ukrainian girls in high jump, maybe Moser (unlikely), Kolak (of course), Warholm, maybe Heß or Babayev (unlikely), Bukowiecki (of course)
I know its early to say, but if we look back at the results of the U20/U23 european championships from this year in a couple of years, we will probably see that more (future) stars competed at the U20 european championships that year.